The thesis is a political narrative in three parts. It has two themes. One is the rise to power of Sir Francis Walsingham. The second is the contention that the promulgation of the plan to marry Elizabeth I to the Duke of Anjou in the period 1579-1581 was more serious, and its consequences more damaging to the interests of the government, than is normally remembered. Against this damaging conduct of policy by his opponents, Walsingham's own ideals are contrasted. Part I explores Walsingham's conduct after appointment as Secretary in 1573. It analyses political conditions at Court, in particular the role of Burghley, and illustrates how by 1578 Walsingham had overturned expectations by allying with Leicester and Hatton. The effectiveness of this alliance is measured by an examination of the success of these three courtiers in cooperating during Walsingham's Embassy to the Netherlands in 1578. A discussion follows of recent writing on patronage and clientage, which concludes that patronage was more often directed by party political considerations than the historians discussed have accepted. This is substantiated by a chapter tracing Walsingham's creation, in Ireland, of a party of followers, of a sophisticated mixture, but in which the influence of common political and religious aims are noted. Part II has two large chapters. The first follows the debates in Council of 1579 in which Burghley propounded the case for the Anjou Marriage, concentrating on the Hatfield papers in which Burghley's thoughts are laid bare, and arguing that his policy was far more peculiar, and less cerebral, than is commonly realised. In order further to demonstrate the linkages between patronage and policy, the remainder of part II traces the impact of the reverses suffered by Leicester and Walsingham at Court on the conduct of English government in Ireland, and foreign policy, especially towards Scotland: the neglect of the earl of Morton is studied in detail through his slow downfall from 1579 to 1581. In conclusion, Walsingham's preferred policy, and its intellectual grounds, are briefly explored. Part III, the shortest of the three, examines each of these three areas of policy for the subsequent impact of the Anjou Marriage perturbations. The thesis concludes that the combination of Burghley and Sussex's marriage policy, and the Queen's more detached preference for procrastinatory diplomatic manoeuvres, had combined to frustrate (in part intentionally) the committedly interventionist and quasi-imperialist policy for which the Protestant party (Walsingham and Leicester, with Hatton, and their evangelical . Protestant followers) had argued. But by 1582, with the marriage clearly impossible of achievement, the Protestant party's agenda was unchallenged.